Chapter 8, Problem 82A

To determine

The reason that the force that act on the axis of rotation of an object can be ignored in static equilibrium while determining the net torque.

Answer to Problem 82A

The torque due to these forces will be zero at the axis of rotation.

Explanation of Solution

Introduction:

The torque is given by,

  $\tau =Fr\sin \theta$

Where, F is the applied force, r is the distance of the point of application of force from the axis of rotation, and $\theta$ is the angle between F and r .

Now, if the axis of rotation is at the point of application of maximum forces, then considering the above formula, the value of $r$ for these forces and thereby the torque due to these forces will be zero.

Conclusion:

Thus, while determining the net torque in static equilibrium, the force that act on the axis of rotation of an object can be ignored since the torque generated due to such forces will be zero.